kernel/trace/synth_event_gen_test.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Test module for in-kernel synthetic event creation and generation.
  *
  * Copyright (C) 2019 Tom Zanussi <zanussi@kernel.org>
  */

 #include <linux/module.h>
 #include <linux/trace_events.h>

 /*
  * This module is a simple test of basic functionality for in-kernel
  * synthetic event creation and generation, the first and second tests
  * using synth_event_gen_cmd_start() and synth_event_add_field(), the
  * third uses synth_event_create() to do it all at once with a static
  * field array.
  *
  * Following that are a few examples using the created events to test
  * various ways of tracing a synthetic event.
  *
  * To test, select CONFIG_SYNTH_EVENT_GEN_TEST and build the module.
  * Then:
  *
  * # insmod kernel/trace/synth_event_gen_test.ko
  * # cat /sys/kernel/tracing/trace
  *
  * You should see several events in the trace buffer -
  * "create_synth_test", "empty_synth_test", and several instances of
  * "gen_synth_test".
  *
  * To remove the events, remove the module:
  *
  * # rmmod synth_event_gen_test
  *
  */

 static struct trace_event_file *create_synth_test;
 static struct trace_event_file *empty_synth_test;
 static struct trace_event_file *gen_synth_test;

 /*
  * Test to make sure we can create a synthetic event, then add more
  * fields.
  */
 static int __init test_gen_synth_cmd(void)
 {
 	struct dynevent_cmd cmd;
 	u64 vals[7];
 	char *buf;
 	int ret;

 	/* Create a buffer to hold the generated command */
 	buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;

 	/* Before generating the command, initialize the cmd object */
 	synth_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);

 	/*
 	 * Create the empty gen_synth_test synthetic event with the
 	 * first 4 fields.
 	 */
 	ret = synth_event_gen_cmd_start(&cmd, "gen_synth_test", THIS_MODULE,
 					"pid_t", "next_pid_field",
 					"char[16]", "next_comm_field",
 					"u64", "ts_ns",
 					"u64", "ts_ms");
 	if (ret)
 		goto free;

 	/* Use synth_event_add_field to add the rest of the fields */

 	ret = synth_event_add_field(&cmd, "unsigned int", "cpu");
 	if (ret)
 		goto free;

 	ret = synth_event_add_field(&cmd, "char[64]", "my_string_field");
 	if (ret)
 		goto free;

 	ret = synth_event_add_field(&cmd, "int", "my_int_field");
 	if (ret)
 		goto free;

 	ret = synth_event_gen_cmd_end(&cmd);
 	if (ret)
 		goto free;

 	/*
 	 * Now get the gen_synth_test event file.  We need to prevent
 	 * the instance and event from disappearing from underneath
 	 * us, which trace_get_event_file() does (though in this case
 	 * we're using the top-level instance which never goes away).
 	 */
 	gen_synth_test = trace_get_event_file(NULL, "synthetic",
 					      "gen_synth_test");
 	if (IS_ERR(gen_synth_test)) {
 		ret = PTR_ERR(gen_synth_test);
 		goto delete;
 	}

 	/* Enable the event or you won't see anything */
 	ret = trace_array_set_clr_event(gen_synth_test->tr,
 					"synthetic", "gen_synth_test", true);
 	if (ret) {
 		trace_put_event_file(gen_synth_test);
 		goto delete;
 	}

 	/* Create some bogus values just for testing */

 	vals[0] = 777;			/* next_pid_field */
 	vals[1] = (u64)(long)"hula hoops";	/* next_comm_field */
 	vals[2] = 1000000;		/* ts_ns */
 	vals[3] = 1000;			/* ts_ms */
 	vals[4] = raw_smp_processor_id(); /* cpu */
 	vals[5] = (u64)(long)"thneed";	/* my_string_field */
 	vals[6] = 598;			/* my_int_field */

 	/* Now generate a gen_synth_test event */
 	ret = synth_event_trace_array(gen_synth_test, vals, ARRAY_SIZE(vals));
  free:
 	kfree(buf);
 	return ret;
  delete:
 	/* We got an error after creating the event, delete it */
 	synth_event_delete("gen_synth_test");
 	goto free;
 }

 /*
  * Test to make sure we can create an initially empty synthetic event,
  * then add all the fields.
  */
 static int __init test_empty_synth_event(void)
 {
 	struct dynevent_cmd cmd;
 	u64 vals[7];
 	char *buf;
 	int ret;

 	/* Create a buffer to hold the generated command */
 	buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;

 	/* Before generating the command, initialize the cmd object */
 	synth_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);

 	/*
 	 * Create the empty_synth_test synthetic event with no fields.
 	 */
 	ret = synth_event_gen_cmd_start(&cmd, "empty_synth_test", THIS_MODULE);
 	if (ret)
 		goto free;

 	/* Use synth_event_add_field to add all of the fields */

 	ret = synth_event_add_field(&cmd, "pid_t", "next_pid_field");
 	if (ret)
 		goto free;

 	ret = synth_event_add_field(&cmd, "char[16]", "next_comm_field");
 	if (ret)
 		goto free;

 	ret = synth_event_add_field(&cmd, "u64", "ts_ns");
 	if (ret)
 		goto free;

 	ret = synth_event_add_field(&cmd, "u64", "ts_ms");
 	if (ret)
 		goto free;

 	ret = synth_event_add_field(&cmd, "unsigned int", "cpu");
 	if (ret)
 		goto free;

 	ret = synth_event_add_field(&cmd, "char[64]", "my_string_field");
 	if (ret)
 		goto free;

 	ret = synth_event_add_field(&cmd, "int", "my_int_field");
 	if (ret)
 		goto free;

 	/* All fields have been added, close and register the synth event */

 	ret = synth_event_gen_cmd_end(&cmd);
 	if (ret)
 		goto free;

 	/*
 	 * Now get the empty_synth_test event file.  We need to
 	 * prevent the instance and event from disappearing from
 	 * underneath us, which trace_get_event_file() does (though in
 	 * this case we're using the top-level instance which never
 	 * goes away).
 	 */
 	empty_synth_test = trace_get_event_file(NULL, "synthetic",
 						"empty_synth_test");
 	if (IS_ERR(empty_synth_test)) {
 		ret = PTR_ERR(empty_synth_test);
 		goto delete;
 	}

 	/* Enable the event or you won't see anything */
 	ret = trace_array_set_clr_event(empty_synth_test->tr,
 					"synthetic", "empty_synth_test", true);
 	if (ret) {
 		trace_put_event_file(empty_synth_test);
 		goto delete;
 	}

 	/* Create some bogus values just for testing */

 	vals[0] = 777;			/* next_pid_field */
 	vals[1] = (u64)(long)"tiddlywinks";	/* next_comm_field */
 	vals[2] = 1000000;		/* ts_ns */
 	vals[3] = 1000;			/* ts_ms */
 	vals[4] = raw_smp_processor_id(); /* cpu */
 	vals[5] = (u64)(long)"thneed_2.0";	/* my_string_field */
 	vals[6] = 399;			/* my_int_field */

 	/* Now trace an empty_synth_test event */
 	ret = synth_event_trace_array(empty_synth_test, vals, ARRAY_SIZE(vals));
  free:
 	kfree(buf);
 	return ret;
  delete:
 	/* We got an error after creating the event, delete it */
 	synth_event_delete("empty_synth_test");
 	goto free;
 }

 static struct synth_field_desc create_synth_test_fields[] = {
 	{ .type = "pid_t",		.name = "next_pid_field" },
 	{ .type = "char[16]",		.name = "next_comm_field" },
 	{ .type = "u64",		.name = "ts_ns" },
 	{ .type = "char[]",		.name = "dynstring_field_1" },
 	{ .type = "u64",		.name = "ts_ms" },
 	{ .type = "unsigned int",	.name = "cpu" },
 	{ .type = "char[64]",		.name = "my_string_field" },
 	{ .type = "char[]",		.name = "dynstring_field_2" },
 	{ .type = "int",		.name = "my_int_field" },
 };

 /*
  * Test synthetic event creation all at once from array of field
  * descriptors.
  */
 static int __init test_create_synth_event(void)
 {
 	u64 vals[9];
 	int ret;

 	/* Create the create_synth_test event with the fields above */
 	ret = synth_event_create("create_synth_test",
 				 create_synth_test_fields,
 				 ARRAY_SIZE(create_synth_test_fields),
 				 THIS_MODULE);
 	if (ret)
 		goto out;

 	/*
 	 * Now get the create_synth_test event file.  We need to
 	 * prevent the instance and event from disappearing from
 	 * underneath us, which trace_get_event_file() does (though in
 	 * this case we're using the top-level instance which never
 	 * goes away).
 	 */
 	create_synth_test = trace_get_event_file(NULL, "synthetic",
 						 "create_synth_test");
 	if (IS_ERR(create_synth_test)) {
 		ret = PTR_ERR(create_synth_test);
 		goto delete;
 	}

 	/* Enable the event or you won't see anything */
 	ret = trace_array_set_clr_event(create_synth_test->tr,
 					"synthetic", "create_synth_test", true);
 	if (ret) {
 		trace_put_event_file(create_synth_test);
 		goto delete;
 	}

 	/* Create some bogus values just for testing */

 	vals[0] = 777;			/* next_pid_field */
 	vals[1] = (u64)(long)"tiddlywinks";	/* next_comm_field */
 	vals[2] = 1000000;		/* ts_ns */
 	vals[3] = (u64)(long)"xrayspecs";	/* dynstring_field_1 */
 	vals[4] = 1000;			/* ts_ms */
 	vals[5] = raw_smp_processor_id(); /* cpu */
 	vals[6] = (u64)(long)"thneed";	/* my_string_field */
 	vals[7] = (u64)(long)"kerplunk";	/* dynstring_field_2 */
 	vals[8] = 398;			/* my_int_field */

 	/* Now generate a create_synth_test event */
 	ret = synth_event_trace_array(create_synth_test, vals, ARRAY_SIZE(vals));
  out:
 	return ret;
  delete:
 	/* We got an error after creating the event, delete it */
 	synth_event_delete("create_synth_test");

 	goto out;
 }

 /*
  * Test tracing a synthetic event by reserving trace buffer space,
  * then filling in fields one after another.
  */
 static int __init test_add_next_synth_val(void)
 {
 	struct synth_event_trace_state trace_state;
 	int ret;

 	/* Start by reserving space in the trace buffer */
 	ret = synth_event_trace_start(gen_synth_test, &trace_state);
 	if (ret)
 		return ret;

 	/* Write some bogus values into the trace buffer, one after another */

 	/* next_pid_field */
 	ret = synth_event_add_next_val(777, &trace_state);
 	if (ret)
 		goto out;

 	/* next_comm_field */
 	ret = synth_event_add_next_val((u64)(long)"slinky", &trace_state);
 	if (ret)
 		goto out;

 	/* ts_ns */
 	ret = synth_event_add_next_val(1000000, &trace_state);
 	if (ret)
 		goto out;

 	/* ts_ms */
 	ret = synth_event_add_next_val(1000, &trace_state);
 	if (ret)
 		goto out;

 	/* cpu */
 	ret = synth_event_add_next_val(raw_smp_processor_id(), &trace_state);
 	if (ret)
 		goto out;

 	/* my_string_field */
 	ret = synth_event_add_next_val((u64)(long)"thneed_2.01", &trace_state);
 	if (ret)
 		goto out;

 	/* my_int_field */
 	ret = synth_event_add_next_val(395, &trace_state);
  out:
 	/* Finally, commit the event */
 	ret = synth_event_trace_end(&trace_state);

 	return ret;
 }

 /*
  * Test tracing a synthetic event by reserving trace buffer space,
  * then filling in fields using field names, which can be done in any
  * order.
  */
 static int __init test_add_synth_val(void)
 {
 	struct synth_event_trace_state trace_state;
 	int ret;

 	/* Start by reserving space in the trace buffer */
 	ret = synth_event_trace_start(gen_synth_test, &trace_state);
 	if (ret)
 		return ret;

 	/* Write some bogus values into the trace buffer, using field names */

 	ret = synth_event_add_val("ts_ns", 1000000, &trace_state);
 	if (ret)
 		goto out;

 	ret = synth_event_add_val("ts_ms", 1000, &trace_state);
 	if (ret)
 		goto out;

 	ret = synth_event_add_val("cpu", raw_smp_processor_id(), &trace_state);
 	if (ret)
 		goto out;

 	ret = synth_event_add_val("next_pid_field", 777, &trace_state);
 	if (ret)
 		goto out;

 	ret = synth_event_add_val("next_comm_field", (u64)(long)"silly putty",
 				  &trace_state);
 	if (ret)
 		goto out;

 	ret = synth_event_add_val("my_string_field", (u64)(long)"thneed_9",
 				  &trace_state);
 	if (ret)
 		goto out;

 	ret = synth_event_add_val("my_int_field", 3999, &trace_state);
  out:
 	/* Finally, commit the event */
 	ret = synth_event_trace_end(&trace_state);

 	return ret;
 }

 /*
  * Test tracing a synthetic event all at once from array of values.
  */
 static int __init test_trace_synth_event(void)
 {
 	int ret;

 	/* Trace some bogus values just for testing */
 	ret = synth_event_trace(create_synth_test, 9,	/* number of values */
 				(u64)444,		/* next_pid_field */
 				(u64)(long)"clackers",	/* next_comm_field */
 				(u64)1000000,		/* ts_ns */
 				(u64)(long)"viewmaster",/* dynstring_field_1 */
 				(u64)1000,		/* ts_ms */
 				(u64)raw_smp_processor_id(), /* cpu */
 				(u64)(long)"Thneed",	/* my_string_field */
 				(u64)(long)"yoyos",	/* dynstring_field_2 */
 				(u64)999);		/* my_int_field */
 	return ret;
 }

 static int __init synth_event_gen_test_init(void)
 {
 	int ret;

 	ret = test_gen_synth_cmd();
 	if (ret)
 		return ret;

 	ret = test_empty_synth_event();
 	if (ret) {
 		WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
 						  "synthetic",
 						  "gen_synth_test", false));
 		trace_put_event_file(gen_synth_test);
 		WARN_ON(synth_event_delete("gen_synth_test"));
 		goto out;
 	}

 	ret = test_create_synth_event();
 	if (ret) {
 		WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
 						  "synthetic",
 						  "gen_synth_test", false));
 		trace_put_event_file(gen_synth_test);
 		WARN_ON(synth_event_delete("gen_synth_test"));

 		WARN_ON(trace_array_set_clr_event(empty_synth_test->tr,
 						  "synthetic",
 						  "empty_synth_test", false));
 		trace_put_event_file(empty_synth_test);
 		WARN_ON(synth_event_delete("empty_synth_test"));
 		goto out;
 	}

 	ret = test_add_next_synth_val();
 	WARN_ON(ret);

 	ret = test_add_synth_val();
 	WARN_ON(ret);

 	ret = test_trace_synth_event();
 	WARN_ON(ret);
  out:
 	return ret;
 }

 static void __exit synth_event_gen_test_exit(void)
 {
 	/* Disable the event or you can't remove it */
 	WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
 					  "synthetic",
 					  "gen_synth_test", false));

 	/* Now give the file and instance back */
 	trace_put_event_file(gen_synth_test);

 	/* Now unregister and free the synthetic event */
 	WARN_ON(synth_event_delete("gen_synth_test"));

 	/* Disable the event or you can't remove it */
 	WARN_ON(trace_array_set_clr_event(empty_synth_test->tr,
 					  "synthetic",
 					  "empty_synth_test", false));

 	/* Now give the file and instance back */
 	trace_put_event_file(empty_synth_test);

 	/* Now unregister and free the synthetic event */
 	WARN_ON(synth_event_delete("empty_synth_test"));

 	/* Disable the event or you can't remove it */
 	WARN_ON(trace_array_set_clr_event(create_synth_test->tr,
 					  "synthetic",
 					  "create_synth_test", false));

 	/* Now give the file and instance back */
 	trace_put_event_file(create_synth_test);

 	/* Now unregister and free the synthetic event */
 	WARN_ON(synth_event_delete("create_synth_test"));
 }

 module_init(synth_event_gen_test_init)
 module_exit(synth_event_gen_test_exit)

 MODULE_AUTHOR("Tom Zanussi");
 MODULE_DESCRIPTION("synthetic event generation test");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Test module for in-kernel synthetic event creation and generation.
	*
	* Copyright (C) 2019 Tom Zanussi <zanussi@kernel.org>
	*/

	#include <linux/module.h>
	#include <linux/trace_events.h>

	/*
	* This module is a simple test of basic functionality for in-kernel
	* synthetic event creation and generation, the first and second tests
	* using synth_event_gen_cmd_start() and synth_event_add_field(), the
	* third uses synth_event_create() to do it all at once with a static
	* field array.
	*
	* Following that are a few examples using the created events to test
	* various ways of tracing a synthetic event.
	*
	* To test, select CONFIG_SYNTH_EVENT_GEN_TEST and build the module.
	* Then:
	*
	* # insmod kernel/trace/synth_event_gen_test.ko
	* # cat /sys/kernel/tracing/trace
	*
	* You should see several events in the trace buffer -
	* "create_synth_test", "empty_synth_test", and several instances of
	* "gen_synth_test".
	*
	* To remove the events, remove the module:
	*
	* # rmmod synth_event_gen_test
	*
	*/

	static struct trace_event_file *create_synth_test;
	static struct trace_event_file *empty_synth_test;
	static struct trace_event_file *gen_synth_test;

	/*
	* Test to make sure we can create a synthetic event, then add more
	* fields.
	*/
	static int __init test_gen_synth_cmd(void)
	{
	struct dynevent_cmd cmd;
	u64 vals[7];
	char *buf;
	int ret;

	/* Create a buffer to hold the generated command */
	buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;

	/* Before generating the command, initialize the cmd object */
	synth_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);

	/*
	* Create the empty gen_synth_test synthetic event with the
	* first 4 fields.
	*/
	ret = synth_event_gen_cmd_start(&cmd, "gen_synth_test", THIS_MODULE,
	"pid_t", "next_pid_field",
	"char[16]", "next_comm_field",
	"u64", "ts_ns",
	"u64", "ts_ms");
	if (ret)
	goto free;

	/* Use synth_event_add_field to add the rest of the fields */

	ret = synth_event_add_field(&cmd, "unsigned int", "cpu");
	if (ret)
	goto free;

	ret = synth_event_add_field(&cmd, "char[64]", "my_string_field");
	if (ret)
	goto free;

	ret = synth_event_add_field(&cmd, "int", "my_int_field");
	if (ret)
	goto free;

	ret = synth_event_gen_cmd_end(&cmd);
	if (ret)
	goto free;

	/*
	* Now get the gen_synth_test event file. We need to prevent
	* the instance and event from disappearing from underneath
	* us, which trace_get_event_file() does (though in this case
	* we're using the top-level instance which never goes away).
	*/
	gen_synth_test = trace_get_event_file(NULL, "synthetic",
	"gen_synth_test");
	if (IS_ERR(gen_synth_test)) {
	ret = PTR_ERR(gen_synth_test);
	goto delete;
	}

	/* Enable the event or you won't see anything */
	ret = trace_array_set_clr_event(gen_synth_test->tr,
	"synthetic", "gen_synth_test", true);
	if (ret) {
	trace_put_event_file(gen_synth_test);
	goto delete;
	}

	/* Create some bogus values just for testing */

	vals[0] = 777; /* next_pid_field */
	vals[1] = (u64)(long)"hula hoops"; /* next_comm_field */
	vals[2] = 1000000; /* ts_ns */
	vals[3] = 1000; /* ts_ms */
	vals[4] = raw_smp_processor_id(); /* cpu */
	vals[5] = (u64)(long)"thneed"; /* my_string_field */
	vals[6] = 598; /* my_int_field */

	/* Now generate a gen_synth_test event */
	ret = synth_event_trace_array(gen_synth_test, vals, ARRAY_SIZE(vals));
	free:
	kfree(buf);
	return ret;
	delete:
	/* We got an error after creating the event, delete it */
	synth_event_delete("gen_synth_test");
	goto free;
	}

	/*
	* Test to make sure we can create an initially empty synthetic event,
	* then add all the fields.
	*/
	static int __init test_empty_synth_event(void)
	{
	struct dynevent_cmd cmd;
	u64 vals[7];
	char *buf;
	int ret;

	/* Create a buffer to hold the generated command */
	buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;

	/* Before generating the command, initialize the cmd object */
	synth_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);

	/*
	* Create the empty_synth_test synthetic event with no fields.
	*/
	ret = synth_event_gen_cmd_start(&cmd, "empty_synth_test", THIS_MODULE);
	if (ret)
	goto free;

	/* Use synth_event_add_field to add all of the fields */

	ret = synth_event_add_field(&cmd, "pid_t", "next_pid_field");
	if (ret)
	goto free;

	ret = synth_event_add_field(&cmd, "char[16]", "next_comm_field");
	if (ret)
	goto free;

	ret = synth_event_add_field(&cmd, "u64", "ts_ns");
	if (ret)
	goto free;

	ret = synth_event_add_field(&cmd, "u64", "ts_ms");
	if (ret)
	goto free;

	ret = synth_event_add_field(&cmd, "unsigned int", "cpu");
	if (ret)
	goto free;

	ret = synth_event_add_field(&cmd, "char[64]", "my_string_field");
	if (ret)
	goto free;

	ret = synth_event_add_field(&cmd, "int", "my_int_field");
	if (ret)
	goto free;

	/* All fields have been added, close and register the synth event */

	ret = synth_event_gen_cmd_end(&cmd);
	if (ret)
	goto free;

	/*
	* Now get the empty_synth_test event file. We need to
	* prevent the instance and event from disappearing from
	* underneath us, which trace_get_event_file() does (though in
	* this case we're using the top-level instance which never
	* goes away).
	*/
	empty_synth_test = trace_get_event_file(NULL, "synthetic",
	"empty_synth_test");
	if (IS_ERR(empty_synth_test)) {
	ret = PTR_ERR(empty_synth_test);
	goto delete;
	}

	/* Enable the event or you won't see anything */
	ret = trace_array_set_clr_event(empty_synth_test->tr,
	"synthetic", "empty_synth_test", true);
	if (ret) {
	trace_put_event_file(empty_synth_test);
	goto delete;
	}

	/* Create some bogus values just for testing */

	vals[0] = 777; /* next_pid_field */
	vals[1] = (u64)(long)"tiddlywinks"; /* next_comm_field */
	vals[2] = 1000000; /* ts_ns */
	vals[3] = 1000; /* ts_ms */
	vals[4] = raw_smp_processor_id(); /* cpu */
	vals[5] = (u64)(long)"thneed_2.0"; /* my_string_field */
	vals[6] = 399; /* my_int_field */

	/* Now trace an empty_synth_test event */
	ret = synth_event_trace_array(empty_synth_test, vals, ARRAY_SIZE(vals));
	free:
	kfree(buf);
	return ret;
	delete:
	/* We got an error after creating the event, delete it */
	synth_event_delete("empty_synth_test");
	goto free;
	}

	static struct synth_field_desc create_synth_test_fields[] = {
	{ .type = "pid_t", .name = "next_pid_field" },
	{ .type = "char[16]", .name = "next_comm_field" },
	{ .type = "u64", .name = "ts_ns" },
	{ .type = "char[]", .name = "dynstring_field_1" },
	{ .type = "u64", .name = "ts_ms" },
	{ .type = "unsigned int", .name = "cpu" },
	{ .type = "char[64]", .name = "my_string_field" },
	{ .type = "char[]", .name = "dynstring_field_2" },
	{ .type = "int", .name = "my_int_field" },
	};

	/*
	* Test synthetic event creation all at once from array of field
	* descriptors.
	*/
	static int __init test_create_synth_event(void)
	{
	u64 vals[9];
	int ret;

	/* Create the create_synth_test event with the fields above */
	ret = synth_event_create("create_synth_test",
	create_synth_test_fields,
	ARRAY_SIZE(create_synth_test_fields),
	THIS_MODULE);
	if (ret)
	goto out;

	/*
	* Now get the create_synth_test event file. We need to
	* prevent the instance and event from disappearing from
	* underneath us, which trace_get_event_file() does (though in
	* this case we're using the top-level instance which never
	* goes away).
	*/
	create_synth_test = trace_get_event_file(NULL, "synthetic",
	"create_synth_test");
	if (IS_ERR(create_synth_test)) {
	ret = PTR_ERR(create_synth_test);
	goto delete;
	}

	/* Enable the event or you won't see anything */
	ret = trace_array_set_clr_event(create_synth_test->tr,
	"synthetic", "create_synth_test", true);
	if (ret) {
	trace_put_event_file(create_synth_test);
	goto delete;
	}

	/* Create some bogus values just for testing */

	vals[0] = 777; /* next_pid_field */
	vals[1] = (u64)(long)"tiddlywinks"; /* next_comm_field */
	vals[2] = 1000000; /* ts_ns */
	vals[3] = (u64)(long)"xrayspecs"; /* dynstring_field_1 */
	vals[4] = 1000; /* ts_ms */
	vals[5] = raw_smp_processor_id(); /* cpu */
	vals[6] = (u64)(long)"thneed"; /* my_string_field */
	vals[7] = (u64)(long)"kerplunk"; /* dynstring_field_2 */
	vals[8] = 398; /* my_int_field */

	/* Now generate a create_synth_test event */
	ret = synth_event_trace_array(create_synth_test, vals, ARRAY_SIZE(vals));
	out:
	return ret;
	delete:
	/* We got an error after creating the event, delete it */
	synth_event_delete("create_synth_test");

	goto out;
	}

	/*
	* Test tracing a synthetic event by reserving trace buffer space,
	* then filling in fields one after another.
	*/
	static int __init test_add_next_synth_val(void)
	{
	struct synth_event_trace_state trace_state;
	int ret;

	/* Start by reserving space in the trace buffer */
	ret = synth_event_trace_start(gen_synth_test, &trace_state);
	if (ret)
	return ret;

	/* Write some bogus values into the trace buffer, one after another */

	/* next_pid_field */
	ret = synth_event_add_next_val(777, &trace_state);
	if (ret)
	goto out;

	/* next_comm_field */
	ret = synth_event_add_next_val((u64)(long)"slinky", &trace_state);
	if (ret)
	goto out;

	/* ts_ns */
	ret = synth_event_add_next_val(1000000, &trace_state);
	if (ret)
	goto out;

	/* ts_ms */
	ret = synth_event_add_next_val(1000, &trace_state);
	if (ret)
	goto out;

	/* cpu */
	ret = synth_event_add_next_val(raw_smp_processor_id(), &trace_state);
	if (ret)
	goto out;

	/* my_string_field */
	ret = synth_event_add_next_val((u64)(long)"thneed_2.01", &trace_state);
	if (ret)
	goto out;

	/* my_int_field */
	ret = synth_event_add_next_val(395, &trace_state);
	out:
	/* Finally, commit the event */
	ret = synth_event_trace_end(&trace_state);

	return ret;
	}

	/*
	* Test tracing a synthetic event by reserving trace buffer space,
	* then filling in fields using field names, which can be done in any
	* order.
	*/
	static int __init test_add_synth_val(void)
	{
	struct synth_event_trace_state trace_state;
	int ret;

	/* Start by reserving space in the trace buffer */
	ret = synth_event_trace_start(gen_synth_test, &trace_state);
	if (ret)
	return ret;

	/* Write some bogus values into the trace buffer, using field names */

	ret = synth_event_add_val("ts_ns", 1000000, &trace_state);
	if (ret)
	goto out;

	ret = synth_event_add_val("ts_ms", 1000, &trace_state);
	if (ret)
	goto out;

	ret = synth_event_add_val("cpu", raw_smp_processor_id(), &trace_state);
	if (ret)
	goto out;

	ret = synth_event_add_val("next_pid_field", 777, &trace_state);
	if (ret)
	goto out;

	ret = synth_event_add_val("next_comm_field", (u64)(long)"silly putty",
	&trace_state);
	if (ret)
	goto out;

	ret = synth_event_add_val("my_string_field", (u64)(long)"thneed_9",
	&trace_state);
	if (ret)
	goto out;

	ret = synth_event_add_val("my_int_field", 3999, &trace_state);
	out:
	/* Finally, commit the event */
	ret = synth_event_trace_end(&trace_state);

	return ret;
	}

	/*
	* Test tracing a synthetic event all at once from array of values.
	*/
	static int __init test_trace_synth_event(void)
	{
	int ret;

	/* Trace some bogus values just for testing */
	ret = synth_event_trace(create_synth_test, 9, /* number of values */
	(u64)444, /* next_pid_field */
	(u64)(long)"clackers", /* next_comm_field */
	(u64)1000000, /* ts_ns */
	(u64)(long)"viewmaster",/* dynstring_field_1 */
	(u64)1000, /* ts_ms */
	(u64)raw_smp_processor_id(), /* cpu */
	(u64)(long)"Thneed", /* my_string_field */
	(u64)(long)"yoyos", /* dynstring_field_2 */
	(u64)999); /* my_int_field */
	return ret;
	}

	static int __init synth_event_gen_test_init(void)
	{
	int ret;

	ret = test_gen_synth_cmd();
	if (ret)
	return ret;

	ret = test_empty_synth_event();
	if (ret) {
	WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
	"synthetic",
	"gen_synth_test", false));
	trace_put_event_file(gen_synth_test);
	WARN_ON(synth_event_delete("gen_synth_test"));
	goto out;
	}

	ret = test_create_synth_event();
	if (ret) {
	WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
	"synthetic",
	"gen_synth_test", false));
	trace_put_event_file(gen_synth_test);
	WARN_ON(synth_event_delete("gen_synth_test"));

	WARN_ON(trace_array_set_clr_event(empty_synth_test->tr,
	"synthetic",
	"empty_synth_test", false));
	trace_put_event_file(empty_synth_test);
	WARN_ON(synth_event_delete("empty_synth_test"));
	goto out;
	}

	ret = test_add_next_synth_val();
	WARN_ON(ret);

	ret = test_add_synth_val();
	WARN_ON(ret);

	ret = test_trace_synth_event();
	WARN_ON(ret);
	out:
	return ret;
	}

	static void __exit synth_event_gen_test_exit(void)
	{
	/* Disable the event or you can't remove it */
	WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
	"synthetic",
	"gen_synth_test", false));

	/* Now give the file and instance back */
	trace_put_event_file(gen_synth_test);

	/* Now unregister and free the synthetic event */
	WARN_ON(synth_event_delete("gen_synth_test"));

	/* Disable the event or you can't remove it */
	WARN_ON(trace_array_set_clr_event(empty_synth_test->tr,
	"synthetic",
	"empty_synth_test", false));

	/* Now give the file and instance back */
	trace_put_event_file(empty_synth_test);

	/* Now unregister and free the synthetic event */
	WARN_ON(synth_event_delete("empty_synth_test"));

	/* Disable the event or you can't remove it */
	WARN_ON(trace_array_set_clr_event(create_synth_test->tr,
	"synthetic",
	"create_synth_test", false));

	/* Now give the file and instance back */
	trace_put_event_file(create_synth_test);

	/* Now unregister and free the synthetic event */
	WARN_ON(synth_event_delete("create_synth_test"));
	}

	module_init(synth_event_gen_test_init)
	module_exit(synth_event_gen_test_exit)

	MODULE_AUTHOR("Tom Zanussi");
	MODULE_DESCRIPTION("synthetic event generation test");
	MODULE_LICENSE("GPL v2");